The present invention relates to a laminating technique and, in particular, to a technique that is effectively applied to a laminator of the type that cuts a continuous thin film to a predetermined size and laminates it over a substrate.
Printed circuit boards used in electronic equipment such as a computers are formed by depositing a predetermined pattern of wires of conductive materials such as copper on one or both sides of an insulating substrate.
Printed circuit boards of this type can be manufactured by the following process.
First, an assembly of a photosensitive resin layer (photoresist) and a transparent resin layer (protective film) is laminated over an electro-conductive layer on the insulating substrate by thermo-compression. This step is commercially carried out with a device called a laminator. Thereafter, a film with a wiring pattern is superposed on the assembly and the photosensitive resin layer is exposed to light for a predetermined period of time through the patterned film and the transparent resin film. Subsequently, the transparent resin film is stripped with a peeler and the exposed photosensitive resin layer is developed to form a mask pattern for etching. Thereafter, the unwanted areas of the conductive layer are etched away and any residual photosensitive layer is removed to produce a printed circuit board having a predetermined wiring pattern.
In the foregoing manufacturing process for the printed circuit boards, it is necessary to provide a step for thermocompression of laminates in an automatic manner by a thin film laminator. The thermocompression laminating process is outlined as follows:
First, a laminate wound continuously on a supply roller of the thin film laminator is supplied to a board or substrate by means of a main vacuum plate. A plurality of absorption holes are formed in a laminate supply surface of the main vacuum plate, so that the laminate is sucked and supplied by the absorption holes. A leading end of the laminate assembly supplied to the substrate is temporarily bonded to a conductive layer of the insulative substrate by an arcuate portion of a temporary bonding portion provided on the leading end side of the main vacuum plate (temporary bonding). The leading end of the laminate may be sucked to the temporary bonding portion by a subvacuum plate that may be close to or away from the laminate supply path. The main and sub vacuum plates are mounted on the laminator body through a support member that may be close to or away from the substrate in order to carry out the supply and temporary bonding operation of the laminate.
Subsequently, the laminate with the leading end being temporarily bonded is thermocompressed onto the substrate by a thermobonding roller. If the laminate is laminated to the substrate to some extent, then the laminate is cut in a predetermined length corresponding to the length of the substrate by means of a cutter. The cutter is provided to the above-described support member together with the main and sub vacuum plates.
However, in such a laminator, if the arcuate temporary bonding portion provided on the supply leading end side of the main vacuum plate would be damaged, it would be necessary to replace the main vacuum plate as a whole by a new one.
Also, when the leading end of the thin film laminate is temporarily bonded to the conductive layer of the insulative substrate by the arcuate temporary bonding portion provided on the supply leading side of the main vacuum plate, a portion other than the temporary bonding portion would be heated so that the photo resist layer (light-sensitive resin layer) would be viscous. This would generate bubbles or the like in the laminated thin film, resulting in fault of bonding.